Data-storage media typically store digital information in discrete locations known as data sectors. The ability of the data sectors of a particular data-storage medium to properly store information is usually checked at some point before the medium reaches the end user. This check is commonly known as a verification. An excessive amount of defective sectors on a data-storage medium may necessitate scrapping the medium. Alternatively, the medium may be utilized after steps have been taken to avoid any future use of the defective sectors.
The relative positions of each defective data sector are sometimes needed by the manufacturer of the data-storage medium in order to identify, diagnose, and correct systemic problems in the production process. For example, several defective sectors oriented along a substantially straight line may be indicative of a manufacturing problem that is placing a scratch on the medium. Hence, manufacturers utilize so-called defect maps that illustrate the positional relationship among defective data sectors. More specifically, a defect map is a graphical representation of the surface of the medium. Symbols are placed on the representation in positions corresponding the locations on the medium at which defective data sectors are located.
Each data sector typically contains specific information that identifies that particular sector. The identities of defective sectors are typically documented by recording this information during the verification process. The sector-identification information alone, however, cannot be utilized to determine the relative positions of the defective sectors. In general, some type of index must be imposed on the surface of the data-storage medium in order to determine these positional relationships. The index furnishes a common reference frame to which the locations of the defective sectors can be related. This type of index is commonly referred to as a hard index.
The use of a hard index presents a number of disadvantages. For example, a hard index consumes data-storage space, thereby reducing the amount of data-storage space available to the user of the data-storage medium. Furthermore, a hard index adds complexity to the medium""s data-storage architecture, and increases the number of steps in the production process for the medium.
Hence, eliminating the need for a hard index to map defects on data-storage media offers potential advantages relating increased data-storage capacity and reduced production costs. The present invention is directed to these and other goals.
An object of the present invention is to provide a method for generating a defect map for a data-storage medium without the use of a hard index. In accordance with this object, a presently-preferred method for generating a defect map for a data-storage medium comprises the step of identifying a defective data sector positioned along a data track on a surface of the data-storage medium. The method also comprises the steps of writing predetermined identification data to the defective data sector, and reading track-location data and the predetermined identification data from the defective data sector.
The presently-preferred method further comprises the steps of reading data from servo sectors positioned along the data track, and updating a count each time the data from one of the servo sectors is read. The method also includes the step of determining a position of the defective data sector on the surface of the data-storage medium based on a value of the count when the identification data from the defective data sector is read, and the track-location data from the defective data sector.
Preferably, the method also includes the steps of generating a graphical representation of the surface of the data-storage medium, superimposing a first symbol on the graphical representation in a position on the graphical representation that corresponds to the position of the defective data sector on the surface of the data-storage medium, and displaying the graphical representation and the symbol on an output device.
In further accordance with the above-noted object of the invention, a presently-preferred method for mapping a defective member of a set of data sectors spaced apart by an equal angular interval along a data track on a surface of a data-storage medium comprises the step of identifying the defective member. The method also includes the steps of writing predetermined identification data to the defective member, and reading track-location data and the predetermined identification data from the defective member.
The presently-preferred method further includes the steps of reading data from servo sectors positioned along the data track, and updating a count each time the data from one of the servo sectors is read. The method also comprises the step of determining an angular position of the defective member on the surface of the data-storage medium by multiplying the angular interval by a value of the count when the identification data from the defective member is read. The method further includes the step of determining a radial position of the defective member on the surface of the data-storage medium based on the track-location data.
Preferably, the method further comprises the step of displaying a graphical representation of the surface of the data-storage medium that includes a symbol located in a position on the graphical representation that corresponds to the angular and the radial positions of the defective member on the surface of the data-storage medium.
A further object of the present invention is to provide a system for generating a defect map for a data-storage medium without the use of a hard index. In accordance with this object, a presently-preferred system for generating a defect map for a data-storage medium comprises a microprocessor and a memory-storage device electrically coupled to the microprocessor.
The presently-preferred system also includes a set of computer-executable instructions stored on the memory-storage device. The computer-executable instructions identify a defective data sector positioned along a data track on a surface of the data-storage medium. The computer-executable instructions also write predetermined identification data to the defective data sector, and read track-location data and the predetermined identification data from the defective data sector. The computer-executable instructions also read data from servo sectors positioned along the data track, and update a count each time the data from one of the servo sectors is read. Furthermore, the computer-executable instructions determine a position of the defective data sector on the surface of the data-storage medium based on a value of the count when the identification data from the defective data sector is read, and the track-location data from the defective data sector.